The present invention relates to a heat insulation assembly for turbo-engines having hollow spaces and including a heat-insulating material enclosed within a heat-resistant cover.
In thermal turbo-engines, such as aircraft turbines or stationary gas turbines, a heat insulation of a housing is, e.g., needed for components arranged inside a gas compressing area, which have a high temperature due to gas compression. With an efficient thermal insulation of the housing relative to the high-temperature components of the turbo-engine, the expansion can be reduced due to the thermal expansion of the housing. In jet engines, for instance, a high thermal expansion of the housing leads to a decrease in efficiency and possibly to complete failure of the jet engine because the tightness needed for the proper operation of the jet engine is lost between the turbine blades rotating inside the jet engine and the sealing elements mounted on the housing when the housing expands radially.
In the prior art as is known from U.S. Pat. No. 49 25 365, the inner housing surfaces which are directly or indirectly exposed to the high-temperature gases in the turbine are covered with a heat insulation assembly. Known heat insulation assemblies have a heat-insulating material enclosed within a stable and temperature-resistant cover. The cover consists of two matching and dimensionally stable metal shells made in a deep-drawing process. To achieve an efficient heat insulation, the metal shells are matched to the inner housing surfaces, which have a complicated structure to permit the arrangement of high-temperature resistant thermal shields, sealing elements and stationary turbine blades. The hollow spaces or recesses formed on the housing wall are, however, not entirely filled because of manufacturing tolerances for the heat insulation elements or, e.g., because of the complicated shape of the hollow spaces, so that there remain free gas-filled spaces in which a heat conduction circumventing the heat insulation is created by heat convection. As a consequence, the heat insulation cannot be optimum, so that the housing has a comparatively high temperature during operation of the turbine, whereby the performance of the turbine is limited because of reduced tightness.